The present invention relates to catalyst systems useful in hydrocarbon upgrading processes and to methods for their production and use.
In another aspect, this invention relates to catalyst systems and processes for oligomerizing hydrocarbons employing the novel catalyst systems of this invention.
Perfluoroalkylsulfonic acids are useful for oligomerization of olefins having in the range of from 3 to 8 carbon atoms per molecule to diesel fuel range hydrocarbons having in the range of from 8 to 24 carbon atoms per molecule. However, many of these compounds are waxy, low surface area solids. The perfluoroalkyl groups of the perfluroalkylsulfonic acids tend to inhibit the dissolution of hydrocarbons into the perfluoroalkylsulfonic acids, and mass transfer limitations occur resulting in low catalyst activity.
Therefore, it is desirable to develop catalyst systems comprising perfluoroalkylsulfonic acid wherein the perfluoroalkylsulfonic acid is supported on a high-surface-area support so as to significantly increase the activity of the perfluoroalkylsulfonic acid in oligomerizing at least one olefin to diesel fuel range hydrocarbons.
It is an object of this invention to provide a novel catalyst system which is useful for at least partially oligomerizing at least one olefin to diesel fuel range hydrocarbons.
A further object of this invention is to provide a method of preparing a novel catalyst system effective for at least partially oligomerizing at least one olefin to diesel fuel range hydrocarbons.
It is a further object of this invention to employ this novel catalyst system as a catalyst in the at least partial oligomerization of at least one olefin to diesel fuel range hydrocarbons.
It is still a further object of the present invention to increase the efficiency of the oligomerization of at least one olefin to diesel fuel range hydrocarbons.
Yet another object of the present invention is to provide an improved oligomerization process of increased efficiency.
According to a first embodiment of the present invention, a method which can be used for producing a catalyst system is provided. The method comprises the steps of:
dissolving at least a portion of at least one perfluoroalkylsulfonic acid salt of the formula CnF2n+1SO3X in a basic solution comprising a base to thereby form a first liquid material, wherein n ranges from 2 to 20 and X is an element selected from the group consisting of sodium and potassium;
dissolving at least a portion of at least one hydrolyzable silane compound in a first acidic solution comprising a first acid to thereby form a second liquid material comprising at least one silanol comprising hydroxy groups and silicon;
mixing the first liquid material and the second liquid material to thereby form a gel comprising silica and the at least one perfluoroalkylsulfonic acid salt;
contacting the gel with a second acidic solution comprising a second acid to thereby form an acid-treated gel and to thereby convert at least a portion of the at least one perfluoroalkylsulfonic acid salt to at least one perfluoroalkylsulfonic acid of the formula CnF2n+1SO3H and to thereby convert at least a portion of the second acid to an acid salt;
removing at least a portion of the acid salt from the acid-treated gel to thereby form a purified gel; and
drying the purified gel to thereby form the catalyst system.
According to a second embodiment of the present invention, an alternative method which can be used for producing a catalyst system is provided. The method comprises the steps of:
mixing at least one perfluoroalkylsulfonic acid salt of the formula CnF2n+1SO3X with silica gel and water to thereby form a gel comprising silica and at least one perfluoroalkylsulfonic acid salt, wherein n ranges from 2 to 20 and X is an element selected from the group consisting of sodium and potassium;
contacting the gel with an acidic solution comprising an acid to thereby form an acid-treated gel and to thereby convert at least a portion of the at least one perfluoroalkylsulfonic acid salt to at least one perfluoroalkylsulfonic acid of the formula CnF2n+1SO3H and to thereby convert at least a portion of the acid to an acid salt;
removing at least a portion of the acid salt from the acid-treated gel to form a purified gel; and
drying the purified gel to thereby form the catalyst system.
According to a third embodiment of the present invention, a process is provided for oligomerizing at least a portion of a hydrocarbon feedstock comprising at least one olefin having in the range of from 3 to 8 carbon atoms per molecule. The process comprises contacting the hydrocarbon feedstock with a catalyst system prepared by the method of the first embodiment or, alternatively, the method of the second embodiment.
Other objects and advantages will become apparent from the detailed description and the appended claims.
According to the first embodiment of the present invention, the catalyst system can be prepared by the following method.
At least a portion of at least one perfluoroalkylsulfonic acid of the formula CnF2n+1SO3H, wherein n ranges from 2 to 20, can be converted to at least one perfluoroalkylsulfonic acid salt of the formula CnF2n+1SO3X, wherein X comprises an element selected from the group consisting of sodium and potassium, by contacting the perfluoroalkylsulfonic acid with a first basic solution comprising water and a compound of the formula XOH. The at least one perfluoroalkylsulfonic acid can be contacted in any suitable manner known to effect the contact of the at least one perfluoroalkylsulfonic acid with the compound. It is preferred for the at least one perfluoroalkylsulfonic acid to be dissolved in an aqueous solution comprising XOH to thereby form the at least one perfluoroalkylsulfonic acid salt.
Alternatively, at least a portion of at least one perfluoroalkylsulfonyl halide of the formula CnF2n+1SO2Y, wherein n ranges from 2 to 20 and Y is a halide selected from the group consisting of chlorine, fluorine, bromine, iodine, astatine and mixtures of any two or more thereof, preferably fluorine and chlorine, can be converted to at least one perfluoroalkylsulfonic acid salt of the formula CnF2n+1SO3X, wherein X comprises an element selected from the group consisting of sodium and potassium, by contacting the perfluoroalkylsulfonyl halide with a first basic solution comprising water and a compound of the formula XOH. The at least one perfluoroalkylsulfonyl halide can be contacted in any suitable manner known to effect the contact of the at least one perfluoroalkylsulfonyl halide with the compound. It is preferred for the at least one perfluoroalkylsulfonyl halide to be dissolved in an aqueous solution comprising XOH to thereby form the at least one perfluoroalkylsulfonic acid salt.
Perfluoroalkylsulfonic acids are not easily purified. Thus, producing a sufficient quantity of purified perfluoroalkylsulfonic acid using typical separation techniques, such as distillation, to produce an effective oligomerization catalyst is extremely expensive and inefficient. However, the perfluoroalkylsulfonic acid salt (as produced above) of the perfluoroalkylsulfonic acid can be easily separated from the aqueous solution, by washing, settling and filtration techniques, resulting in a purified perfluoroalkylsulfonic acid salt.
The purified at least one perfluoroalkylsulfonic acid salt can be dissolved in a basic solution comprising a base comprising hydroxy groups to form a first liquid material.
At least one hydrolyzable silane compound can be dissolved in a first acidic solution comprising a first acid and water to thereby form a second liquid material comprising at least one silanol comprising hydroxy groups and silicon.
Suitable hydrolyzable silane compounds include, but are not limited to, alkoxysilane compounds, preferably, tetramethoxysilane and tetraethoxysilane.
Any suitable acid effective in hydrolyzing the hydrolyzable silane compound can be used as the first acid. Preferably, the first acid is hydrochloric acid.
The first liquid material and second liquid material can be mixed in any suitable manner, including, but not limited to, stirring or blending, sufficient to effect a thorough mixing so as to form a gel comprising silica (SiO2) and the at least one perfluoroalkylsulfonic acid salt.
The gel can then be contacted with a second acidic solution comprising a second acid to thereby form an acid-treated gel and to thereby convert at least a portion of the at least one perfluoroalkylsulfonic acid salt to at least one perfluoroalkylsulfonic acid of the formula CnF2n+1SO3H.
Any suitable acid effective in converting at least a portion of the at least one perfluoroalkylsulfonic acid salt to at least one perfluoroalkylsulfonic acid can be used as the second acid. Preferably, the second acid is sulfuric acid.
More particularly, the contacting of the gel with the second acidic solution results in the at least partial conversion of the at least one perfluoroalkylsulfonic acid salt of the formula CnF2n+1SO3X to the at least one perfluoroalkylsulfonic acid of the formula CnF2n+1SO3H and the at least partial conversion of the acid to its acid salt. The preferred acid, sulfuric acid (H2SO4), is at least partially converted to its acid salt (X2SO4).
The acid-treated gel can then be washed with water in order to at least partially remove the acid salt to thereby form a purified gel.
The purified gel can then be dried at a temperature of between about 140xc2x0 F. (60xc2x0 C.) and about 180xc2x0 F. (82.2xc2x0 C.) to thereby form the catalyst system. Preferably, the drying is performed under vacuum conditions and for greater than 2 hours.
Optionally, a platinum group metal compound can be incorporated into the catalyst system, by any suitable manner, to provide active sites to aid in catalyst regeneration. As used herein, platinum group metals include, but are not limited to, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium and platinum.
According to the second embodiment of the present invention, the catalyst system can alternatively be prepared by the following method.
The at least one perfluoroalkylsulfonic acid salt can be prepared by the method described above in the first embodiment.
The at least one perfluoroalkylsulfonic acid salt can be combined, by mixing, stirring or blending, with a silica gel and water to thereby form a gel comprising silica and the at least one perfluoroalkylsulfonic acid salt.
The gel can then be contacted with an acidic solution comprising an acid to thereby form an acid-treated gel and to thereby convert at least a portion of the at least one perfluoroalkylsulfonic acid salt to at least one perfluoroalkylsulfonic acid of the formula CnF2n+1SO3H.
Any suitable acid effective in converting at least a portion of the at least one perfluoroalkylsulfonic acid salt to at least one perfluoroalkylsulfonic acid can be used as the acid. Preferably, the acid is sulfuric acid.
More particularly, the contacting of the gel with the acidic solution results in the at least partial conversion of the at least one perfluoroalkylsulfonic acid salt of the formula CnF2n+1SO3X to the at least one perfluoroalkylsulfonic acid of the formula CnF2n+1SO3H and the at least partial conversion of the acid to its acid salt. The preferred acid, sulfuric acid (H2SO4), is at least partially converted to its acid salt (X2SO4).
The acid-treated gel can then be washed with water in order to at least partially remove the acid salt to thereby form a purified gel.
The purified gel can then be dried at a temperature of between about 140xc2x0 F. (60xc2x0 C.) and about 180xc2x0 F. (82.2xc2x0 C.) to thereby form the catalyst system. Preferably, the drying is performed under vacuum conditions and for greater than 2 hours.
Optionally, a platinum group metal compound can be incorporated into the catalyst system, by any suitable manner, to provide active sites to aid in catalyst regeneration.
According to the third embodiment of the present invention, a process useful for oligomerizing at least a portion of a hydrocarbon feedstock comprises, consists essentially of, or consists of contacting the hydrocarbon feedstock with a catalyst system under conditions sufficient to effect the oligomerization of at least a portion of the hydrocarbon feedstock. The catalyst system can be produced by the method of the first embodiment or, alternatively, by the method of the second embodiment.
The term xe2x80x9chydrocarbon feedstockxe2x80x9d is generally referred to, unless otherwise indicated, as one or more hydrocarbons or substituted hydrocarbons having in the range of from about 2 carbon atoms to about 30 carbon atoms, preferably about 3 to about 20, and most preferably 3 to 16 carbon atoms per molecule. Non-limiting examples of suitable hydrocarbon feedstocks include gasolines from catalytic oil cracking (e.g., FCC and hydrocracking) processes, pyrolysis gasolines from thermal hydrocarbon (e.g., ethane, propane, and naphtha) cracking processes, coker naphtha, light coker naphtha, straight run naphtha, light naphtha and the like. The most preferred hydrocarbon feedstock comprises at least one olefin containing in the range of from 3 to 10 carbon atoms per molecule.
Generally, the hydrocarbon feedstock is contacted with the inventive catalyst system contained in an oligomerization zone. The hydrocarbon feedstock can be contacted with the inventive catalyst system by any suitable manner. The contacting step can be operated as a batch process step or, preferably, as a continuous process step. In the latter operation, a solid catalyst bed or a moving catalyst bed or a fluidized catalyst bed can be employed. Any of these operational modes has advantages and disadvantages, and those skilled in the art can select the one most suitable for a particular feed and catalyst system.
The contacting step is preferably carried out within an oligomerization zone, wherein is contained the inventive catalyst system, and under reaction conditions that suitably promote oligomerization of at least a portion of the unsaturated hydrocarbons of the hydrocarbon feedstock. The reaction temperature of the oligomerization zone is more particularly in the range of from about 150xc2x0 F. (65.6xc2x0 C.) to about 300xc2x0 F. (148.9xc2x0 C.), preferably in the range of from about 190xc2x0 F. (87.8xc2x0 C.) to about 260xc2x0 F. (126.7xc2x0 C.), and most preferably in the range of from 200xc2x0 F. (93.3xc2x0 C.) to 240xc2x0 F. (115.6xc2x0 C.). The oligomerization zone is operated at a pressure sufficient to maintain the reactants in liquid form. The contacting pressure of the oligomerization zone is generally within the range of from about 0 psig to about 1000 psig, preferably in the range of from about 50 psig to about 500 psig, and most preferably from 100 psig to 250 psig.
The flow rate at which the hydrocarbon feedstock is charged to the oligomerization zone is such as to provide a weight hourly space velocity (xe2x80x9cWHSVxe2x80x9d) in the range of from exceeding 0 hourxe2x88x921 upwardly to about 1000 hourxe2x88x921. The term xe2x80x9cweight hourly space velocityxe2x80x9d, as used herein, shall mean the numerical ratio of the rate at which a hydrocarbon feedstock is charged to the oligomerization zone in pounds per hour divided by the pounds of catalyst contained in the oligomerization zone to which the hydrocarbon feedstock is charged. The preferred WHSV of the hydrocarbon feedstock to the oligomerization zone is preferably in the range of from about 0.25 hourxe2x88x921 to about 250 hourxe2x88x921 and, most preferably, in the range of from 0.5 hourxe2x88x921 to 100 hourxe2x88x921.
The following examples are presented to further illustrate the invention and are not to be construed as unduly limiting its scope.